The prior art bead locking devices teach the use of open structures, closed structures,, and a combination of each, as well as pneumatic and mechanical sealing mechanisms. The prior art also teaches some form of cross member or run flat structure for supporting the tire during periods of low pressure. An open structure is one that has a space or gap between successive cross members. A closed structure is one in which the cross member is a continuous structure. A combination structure is a partially open and partially closed structure. A pneumatic seal uses air pressure to lock the tire bead in place. A mechanical seal uses a mechanical device to lock the tire bead in place.
The following groups of patents illustrate different bead-lock and run-flat devices. U.S. Pat. Nos. 1,324,944 issued to Watkins; 1,213,557 issued to Trotter; 4,157,107 issued to Cataldo; 4,223,713 issued to Ewing; 4,246,947 issued to Ewing; EPO No. 00020150 issued to Furusawa, and British Pat. No. 1,305,383 issued to Gillett illustrate varying forms of an open structure run-flat device. U.S. Pat. Nos. 2,844,180 issued to Omeron; 3,838,836 issued to Bradley; 4,248,286 issued to Curtis; 4,293,016 issued to Bible; 4,401,144 issued to Wilde, and German Pat. No. 2,648,919 issued to Lepper illustrate varying forms of a closed structure. U.S. Pat. Nos. 4,281,700 and 4,281,701 issued to Ross illustrate a form of combination run-flat and bead lock device. U.S. Pat. Nos. 4,153,095 issued to Sarkissian; 4,216,809 issued to Picksley; 4,246,948 and 4,262,724 issued to Sarkissian illustrate a pneumatic sealing bead-lock device. U.S. Pat. Nos. 2,053,545 issued to Girz and 4,216,810 issued to Osada illustrate a mechanical sealing bead-lock device.
The above-identified prior art patents that teach run-flat and bead-lock devices have, however, several disadvantages. One disadvantage is the fact that many of them are made of heavy metallic materials, adding excessive inefficient weight in operation, as well as in handling. There are disadvantages in the use of pneumatic sealing devices as well. These devices are usually lighter than metallic devices but they can lose their air pressure just like the tires thereby effectively destroying their bead locking function. Moreover, they are generally somewhat complex structures and are not capable of easy repair.
Those skilled in the art may be aware of still other disadvantages in the use of the types of bead-lock and run-flat devices mentioned herein and commonly used in the field.